“…Defects in some regulator mechanism necessary to maintain a balanced function; changes in the bronchial ground substance (Rappaport et al, 1953), or changed permeability conditions there (McCarter and Vazquez, 1966;Samter, 1959); pathological reactivity of 3-adrenergic or cholinergic receptors in the bronchi (Kirkpatrick and Keller, 1967;Ouellette and Reed, 1965); or imbalance of local enzyme systems (Ann. Allergy, 1965;Ungar and Hayashi, 1958) all merit attention in this challenging field.…”